Conventionally, in a vehicle such as a station wagon and a minivan, a side portion of its body is provided with a sliding door (i.e., opening and closing body) which is opened and closed in vehicle-front and vehicle-back directions, thereby allowing passengers or baggage to be easily loaded or unloaded from the vehicle. This sliding door can normally be opened and closed by manual operation. However, in recent years, a driving apparatus is provided in the vicinity of a slide door in many vehicles so as to automatically open and close the slide door.
As a driving apparatus for opening and closing a slide door, so-called “cable-type driving apparatus” is known, and this driving apparatus is configured to pull a cable connected to a slide door in front and rear directions of a vehicle via two pulleys which are provided at respective ends of a guide rail for guiding the slide door. The cable is wound on a drum rotatably provided in a vehicle body, and a winding direction of the cable on the drum is switched by causing the electric motor to driving the drum so as to rotate the drum in a foreword direction or in a reverse direction, so that the slide door is opened or closed.
As this cable-type driving apparatus, for example, a driving apparatus described in Japanese Patent Application Laid-Open Publication No. 2008-025290 is known. The driving apparatus (automatic opening and closing apparatus for vehicle) described in Japanese Patent Application Laid-Open Publication No. 2008-025290 is provided with: a worm wheel forming a reduction mechanism; and an electromagnetic clutch for performing switching between a manual opening and closing operation and an automatic opening and closing operation of a slide door are provided to be coaxial with the drum. The reduction mechanism is composed of the worm wheel and a worm meshing with the worm wheel, and rotation shafts of the worm wheel and the worm are perpendicular to each other.
The electromagnetic clutch is configured to couple the worm wheel with the drum, and to separate them from each other, and turning force of the worm is transmitted to the drum via the worm wheel in the coupled state, that is, the slide door can be opened and closed automatically. On the other hand, in the separated state, the drum can be freely rotated without being restricted by the worm wheel, so that the slide door can be opened and closed manually.
Thus, since the driving apparatus described in Japanese Patent Application Laid-Open Publication No. 2008-025290 is provided with a worm and a worm wheel (reduction mechanism), and they have respective rotation shafts perpendicular to each other, the turning force of the worm wheel cannot be transmitted to the worm. Therefore, the driving apparatus described in Japanese Patent Application Laid-Open Publication No. 2008-025290 is provided with an electromagnetic clutch for performing switching between the manual opening and closing operation and the automatic opening and closing operation.